Wireless communication terminal and QoS information collection method

ABSTRACT

In a wireless communication terminal, the other terminal existence confirmation section broadcasts a confirmation message at fixed intervals and receives a response message. The topology information management section computes the topology of the whole network to which the wireless communication terminal itself belongs, on the basis of the topology information on the network received at fixed intervals from other terminals. The path management section derives an optimum path to the terminal of the transmission destination. The QoS information collection section issues a communication start request instruction and, when a QoS information collect request instruction has been issued, unicasts a QoS request packet on the path and receives a reply QoS request packet. The judgment section adopts the path as the communication path when QoS information satisfies a predetermined quality standard.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wireless communication terminal andQoS information collection method.

2. Related Background Art

An adhoc network is constituted by autonomous user terminals e.g.,personal digital assistants (PDA), personal computers, wirelesscommunication terminals such as cellular phones, and links among therespective wireless communication terminals. A base station, an accesspoint and so forth that manages the wireless communication terminalsdoes not exist in this adhoc network. Therefore, routing is required byeach of the wireless communication terminals before startingcommunications. As a result of the routing, it is determined where thecommunication-destination wireless communication terminal is and whichwireless communication terminal communications are to be routed throughfor communication with the terminal. The protocols for routing in suchad-hoc networks include the proactive-type routing protocol, forexample.

In a proactive-type routing protocol, the respective wirelesscommunication terminals have a routing table for storing pathinformation to other wireless communication terminals on the network.Here, the path information stored in the routing table is found asfollows, for example. First, the topology, which is the connection formof the network, is determined on the basis of topology information thatis exchanged at fixed intervals between the respective wirelesscommunication terminals. Path information to the other wirelesscommunication terminals is then found on the basis of the topology. Byusing a routing table in which such path information is stored, therespective wireless communication terminals are always able to grasp thepath to the respective transmission destinations irrespective of whethercommunication exists.

In an adhoc network of this kind, because the states of the links changeat any time unlike a wired network, the communication quality such asthe bandwidth and delay and so forth also accordingly changes at anytime. Hence, in an adhoc network requiring a high communication quality,information on the existence of a link as well as link QoS (Quality ofService) information must be exchanged between the respective wirelesscommunication terminals.

When QoS information is exchanged by using an proactive-type routingprotocol, the topology information is exchanged at fixed intervalsbetween the respective wireless communication terminals after the QoSinformation on the links has also been added to the information on theexistence of links contained in the topology information (See Document1: ‘Hakim Badis, Anelise Munaretto, Khaldoun Al Agha and Guy Pujolle,“QoS for Ad-hoc Networking Based on Multiple Metrics: Bandwidth andDelay”, In the Proceedings of the 5^(th) IFIP TC6 InternationalConference on Mobile and Wireless Communication Networks (MWCN'03),IEEE, Singapore, October 2003.’ and Document 2 ‘Ying Ge, Thomas Kunz andLouise Lamont, “Quality of Service Routing in Ad-hoc Networks UsingOLSR”, in the Proceedings of the 36^(th) Hawaii International Conferenceon System Sciences (HICSS'03), IEEE, 2003.’ As a result, a path to thetransmission destination can be constructed by the respective wirelesscommunication terminals and the quality of the path can be judged.Hence, when a plurality of paths to the transmission destination exist,communication can be performed by selecting the path with the optimumquality.

Further, when QoS information that uses the proactive-type routingprotocol is exchanged, QoS information on the links is also added to thetopology information exchanged at fixed intervals. Hence, the amount ofconsumption of terminal resources such as the CPU and memory andwireless resources such as the communication bandwidth increases and theload on the network increases.

SUMMARY OF THE INVENTION

Further, in order to determine the above problem, an object of thepresent invention is to provide a wireless communication terminal andQoS information collection method capable of reducing the amount ofconsumption of terminal resources and wireless resources in order toreduce the load on the network.

The wireless communication terminal of the present invention comprisesother terminal existence confirmation means for confirming the existenceof another wireless communication terminal that allows mutual directwireless communication with the wireless communication terminal itself;topology information management means for managing information relatingto the other wireless communication terminal confirmed by the otherterminal existence confirmation means and information on the topology ofthe network that is received from the other wireless communicationterminal; path derivation means for deriving the optimum path to thetransmission destination on the basis of the topology informationmanaged by the topology information management means; and QoSinformation collection means for collecting QoS (Quality of Service)information for at least a portion of the path when a collect requestinstruction requesting that QoS information on the path derived by thepath derivation means be collected.

Further, the QoS information collection method of the present inventioncomprises an other terminal existence confirmation step in which thewireless communication terminal confirms the existence of anotherwireless communication terminal that allows mutual direct wirelesscommunication with the wireless communication terminal itself; atopology information management step in which the wireless communicationterminal manages information relating to the other wirelesscommunication terminal confirmed by the other terminal existenceconfirmation step and information on the topology of the network that isreceived from the other wireless communication terminal; a pathderivation step in which the wireless communication terminal derives theoptimum path to the transmission destination on the basis of thetopology information managed by the topology information managementstep; and a QoS information collection step in which the wirelesscommunication terminal collects QoS information for at least a portionof the path when a collect request instruction requesting that QoSinformation on the path derived by the path derivation means becollected.

According to these inventions, another wireless communication terminalthat allows mutual direct wireless communication with the wirelesscommunication terminal itself is able to reliably grasp the existence ofa so-called ‘one hop neighbor’ and receive topology information on thenetwork from the one hop neighbor. Therefore, the connection form of thewhole network can always be grasped. Furthermore, the optimum path tothe transmission destination can be derived based on the receivedtopology information. Hence, only the optimum path can be managed amongthe paths to the transmission destination. Further, only when a QoSinformation collect request instruction is received, QoS information onall or a portion of the paths can be collected. Hence, QoS informationcan be collected only when necessary. That is, according to the presentinvention, QoS information can be collected only on the required pathonly when necessary. In addition, not only the QoS informationcomputation amounts of the respective communication terminals on thenetwork, the QoS information exchange amounts and propagation amountsbetween the respective communication terminals can be suppressed, butalso the amounts of consumption of the terminal resources and wirelessresources and so forth can be reduced and the load on the network can bereduced.

In the case of the wireless communication terminal of the presentinvention, the QoS information collection means preferably collects theQoS information by transmitting packets in which at least QoS itemswhich are collection targets are stored on a path derived by pathderivation means and by receiving packets in which at least the QoSinformation corresponding with the QoS items are stored on the path.Thus, QoS information corresponding with the desired QoS items can beefficiently collected.

In the case of the wireless communication terminal of the presentinvention, the QoS information collected by the QoS informationcollection means desirably further comprises path adoption means thatadopt a path corresponding to the QoS information when a predeterminedquality standard is satisfied. Thus, a wireless communicationenvironment that satisfies a predetermined quality standard can beprovided.

According to the wireless communication terminal of the presentinvention, when a plurality of paths are derived by the path derivationmeans, the QoS information collection means preferably collects therespective QoS information on the plurality of paths. Thus, even in acase where communication is performed by using a plurality of paths,only the QoS information on the path required for communication can becollected.

The wireless communication terminal and QoS information collectionmethod of the present invention make it possible to reduce the terminalresource and wireless resource consumption amounts and to reduce theload on the network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the network configuration of an adhoc network of anembodiment.

FIG. 2 is a block diagram that illustrates the functional constitutionof the cellular phone shown in FIG. 1.

FIG. 3 illustrates the data constitution of the routing table.

FIG. 4 illustrates the constitution of QoS request packet.

FIG. 5 illustrates the constitution of a response QoS request packet.

FIG. 6 is a flowchart that illustrates the flow of the routingprocessing.

FIG. 7 illustrates the network configuration of the adhoc network of amodified example.

FIG. 8 illustrates the data configuration of a routing table of themodified example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the wireless communication terminal and QoS informationcollection method according to the present invention will now bedescribed with reference to the drawings. Further, a repetitivedescription is avoided by assigning the same codes to the same elementsin the respective drawings.

FIG. 1 illustrates the constitution of the adhoc network 1 of thisembodiment. As shown in FIG. 1, the adhoc network 1 comprises a cellularphone 10 constituting a node, and links 20 between the respectivecellular phones 10. The links 20 are bidirectional links. The cellularphones 10 at both ends of the links 20 are able to perform directwireless communication with one another. One link 20 is known as one hopand a cellular phone capable of performing direct wireless communicationis known as a one hop neighbor. Cellular phones between which links 20do not exist are unable to perform direct wireless communication.

Further, in this embodiment, a specific example of the wirelesscommunication terminal will be described by using the cellular phone 10but the specific example of the wireless communication terminal is notlimited to the cellular phone 10. The wireless communication terminalmay be a simple cellular phone (PHS), a mobile communication terminalsuch as a personal digital assistant (PDA) with a wireless communicationfunction, a fixed communication terminal such as a personal computerwith a wireless communication function, or an electronic device such asa printer with a wireless communication function, for example.

The functional constitution of the cellular phone 10 of this embodimentwill be described next with reference to FIG. 2. As shown in FIG. 2, thecellular phone 10 comprises an other cellular phone existenceconfirmation section 11 (other terminal existence confirmation means), atopology information management section 12 (topology informationmanagement means), a path management section 13 (path derivation means),a QoS information collection section 14 (QoS information collectionmeans), and a judgment section 15 (path adoption means).

The other cellular phone existence confirmation section 11 confirms theexistence of another cellular phone that allows direct wirelesscommunication to be performed mutually with the cellular phone 10itself. When this is described in specific terms, the other cellularphone existence confirmation section 11 broadcasts a confirmationmessage to all the other cellular phones that exist in the peripherythereof at fixed intervals (every two seconds, for example). As aconfirmation message, a HELLO Packet applies, for example. The othercellular phone existence confirmation section 11 receives a responsemessage to the broadcast confirmation messages. The response messagecontains an ID for uniquely specifying the cellular phone that is thesource of the response. As a result, the cellular phone 10 is able toconfirm the existence of other cellular phones which are one hopneighbors. Further, the method and frequency at which a confirmationmessage and response message are exchanged is not limited to the abovemethod and frequency. In short, as long as the existence of anothercellular phone constituting a one hop neighbor can be confirmed, anymethod and frequency can be used. However, a change in one hop neighborscan be grasped more reliably by increasing the frequency and the amountof consumption of the terminal resources and wireless resources and soforth can be reduced further by reducing the frequency.

The topology information management section 12 computes the topologyrepresenting the connection form of the overall network to which its owncellular phone belongs on the basis of information relating to othercellular phones confirmed by the other cellular phone existenceconfirmation section 11 and topology information on the network that isreceived at fixed intervals from the other cellular phone, and storesthe topology in memory. As information relating to the other cellularphones, the IDs of the other cellular phones apply, for example. Asnetwork topology information, one hop neighbor-related information onother cellular phones applies, for example. Thus, protocols forcomputing and managing the topology of the network while exchangingtopology information at fixed intervals with other cellular phonesinclude OLSR (Optimized Link State Routing Protocol) and TBRPF (TopologyDissemination Based on Reverse-Path Forwarding), for example.

Further, in the case of OLSR, Reference Document 1 (T. Clausen and P.Jacquet, “Optimized Link State Routing Protocol(OLSR)”, RFC3626,October, 2003,http://ftp.jaist.ac.jp/pub/Internet/RFC.pdf/rfc3626.txt.pdf) wasreferenced and the content thereof was incorporated into the disclosedcontent of this specification. Further, with regard to TBRPF, ReferenceDocument 2 (R. Ogier, F. Templin and M. Lewis “Topology DisseminationBased on Reverse-Path Forwarding (TBRPF)”, RFC3684, February, 2004,http://ftp.jaist.ac.jp/pub/Internet/RFC.pdf/rfc3684.txt.pdf) wasreferenced and the content thereof was incorporated into the disclosedcontent of this specification.

The path management section 13 derives the optimum path to the cellularphone of the transmission destination on the basis of the topologycomputed by the topology information management section 12 and manages arouting table 18 on the basis of the derived path. When this isdescribed in specific terms, the path management section 13 firstderives the paths to the transmission destinations on the basis of thetopology. The path management section 13 then selects the path with thesmallest number of links to the transmission destination among thederived paths as the optimum path to the transmission destination.Thereafter, the path management section 13 creates or updates therouting table 18 on the basis of the selected optimum path.

Here, the table constitution of the routing table 18 will be describedwith reference to FIG. 3. The routing table 18 has ‘Transmissiondestination’ and ‘Next hop’, for example, as data items. An ID foruniquely specifying the cellular phone constituting the communicationpartner destination is stored for the transmission destination. An IDfor uniquely specifying the cellular phones on the path constituting thetransmission destination among the one hop neighbors is stored as theNext hop. That is, the ID of the cellular phone that the communicationfirst passes through when communicating with the transmissiondestination among the cellular phones on the optimum path to thetransmission destination is stored as the Next hop.

The path management section 13 updates information relating to the othercellular phones confirmed by the other cellular phone existenceconfirmation section 11 or updates the content of the routing table 18when there is a change in the topology computed by the topologyinformation management section 12. As a result, the routing table 18 iscapable of storing the latest path information to the other cellularphones.

The QoS information collection section 14 receives a communication startrequest instruction that requests the start of communication and, when acollect request instruction that requests that QoS information on thepath be collected is received, the QoS information collection section 14collects QoS information on the path derived by the path managementsection 13. The communication start request instruction is aninstruction that is output within the terminal as a result of therequest for the application when the path to the communication partnerdestination used in data communication or control signal communicationis required. The collect request instruction is an instruction that isoutput within the terminal together with the communication start requestinstruction.

The method of collecting QoS information will be described hereinbelow.First, the QoS information collection section 14 unicasts the QoSrequest packet shown in FIG. 4 on the path derived by the pathmanagement section 13.

The address of the cellular phone of the transmission destination andthe address of the cellular phone of the transmission source are storedin the QoS request packet shown in FIG. 4 and one or a plurality of QoSitems which are collection targets are stored therein. QoS items includethe bandwidth, delay, and link error rate, for example. The QoS itemswhich are the collection targets are optionally set on the communicationapplication side.

Thereafter, the respective cellular phones on the path whereon the QoSrequest packet is received store QoS information computed by therespective cellular phones in a predetermined storage location for QoSrequest packets.

Thereafter, when the QoS request packet reaches the cellular phone whichis the transmission destination, the reply QoS request packet shown inFIG. 5 is sent back to the cellular phone constituting the transmissionsource. The address of the transmission-destination cellular phone andthe address of the transmission-source cellular phone are stored in thereply QoS request packet shown in FIG. 5 and QoS informationcorresponding with the QoS item of the respective links on the path arestored therein. Further, the address of the cellular phone constitutingthe transmission source of the QoS request packet and the address of thetransmission-destination cellular phone are stored as the transmissionsource and transmission destination of the reply QoS request packet.

Thereafter, the reply QoS request packet is received by thetransmission-source cellular phone. As a result, the transmission-sourcecellular phone is able to collect the QoS information on the path. QoSinformation corresponding with the desired QoS item can be collectedefficiently by collecting QoS information by using such a QoS requestpacket.

The judgment section 15 judges whether the QoS information collected bythe QoS information collection section 14 satisfies a predeterminedquality standard. When it is judged that the QoS information satisfiesthe predetermined quality standard, the judgment section 15 adopts apath derived by the path management section 13 as the path used duringcommunication. On the other hand, when the judgment section 15 judgesthat a predetermined quality standard has not been satisfied for QosInformation, the judgment section 15 sends a path request instructionrequesting that another path be derived to the path management section13. As a result, the user can be provided with a wireless communicationenvironment that satisfies a predetermined quality standard.

The flow of the routing processing that includes the QoS collectprocessing that is performed by the cellular phone 10 of this embodimentwill be described next with reference to FIG. 6.

First, the other cellular phone existence confirmation section 11 of thecellular phone 10 broadcasts a confirmation message at fixed intervalsto all the other cellular phones that exist in the periphery thereof(step S1). The other cellular phone existence confirmation section 11receives a response message in response to the broadcast confirmationmessage (step S2).

Thereafter, the topology information management section 12 computes andexchanges the topology representing the connection form of the wholenetwork to which its own cellular phone belongs on the basis ofinformation relating to other cellular phones confirmed by the othercellular phone existence confirmation section 11 and network topologyinformation received at fixed intervals from the other cellular phones(step S3).

Thereafter, the path management section 13 derives the optimum path onthe basis of the topology computed by the topology informationmanagement section 12 (step S4) and creates or updates the routing table18 on the basis of the derived path (step S5).

The processing as far as steps S1 to S5 above is repeated irrespectiveof whether the processing described hereinbelow is executed.

Thereafter, when the path management section 13 has output acommunication start request instruction requesting that communication bestarted (step S6; YES), the QoS information collection section 14 judgeswhether a collect request instruction requesting that QoS information onthe path be collected has been output (step S7). When the judgment is NO(step S7; NO), the processing is moved to step S11 (describedsubsequently).

On the other hand, when it is judged in the judgment of step S7 that thecollect request instruction has been output (step S7; YES), the QoSinformation collection section 14 unicasts a QoS request packet on thepath derived by the path management section 13 (step S8).

Thereafter, the QoS information collection section 14 receives a replyQoS request packet in which QoS information is stored by the respectivecellular phones on the path (step S9).

The judgment section 15 then judges whether the QoS informationcollected by the QoS information collection section 14 satisfies apredetermined quality standard (step S10).

When the judgment is NO (step S10; NO), the judgment section 15 sends apath request instruction requesting that another path be derived to thepath management section 13 and moves the processing to step S7.

On the other hand, when it is judged in the judgment of step S10 thatthe QoS information satisfies the predetermined quality standard (stepS10; YES), the judgment section 15 adopts the path derived by the pathmanagement section 13 as the communication path (step S11).

As mentioned earlier, the cellular phone 10 of this embodiment is ableto reliably grasp the existence of another cellular phone that allowsmutual direct wireless communication with the cellular phone 10 itself,that is, a so-called one hop neighbor, and is able to receive topologyinformation on the network from the one hop neighbors. Hence, theconnection form of the whole network can always be grasped. Further, theoptimum path to the transmission destination can be derived on the basisof the received topology information. Therefore, only the optimum pathamong the paths to the transmission destination can be managed. Inaddition, the QoS information on the path can be collected only when aQoS information collect request instruction is output. Therefore, QoSinformation can be collected only when necessary. That is, the presentinvention allows QoS information on the optimum path, that is, only onthe path stored in the routing table 18, to be collected only whennecessary. Hence, not only can the QoS information computation amountsof the respective cellular phones 10 on the network and the QoSinformation exchange amounts and propagation amounts between therespective cellular phones 10 be suppressed but the amounts ofconsumption of the terminal resources and wireless resources and soforth can also be reduced and the load on the network can be reduced.

Further, although a case where there is one path to the transmissiondestination was described in the embodiment above, the present inventioncan also be applied to a case where there are a plurality of paths tothe transmission destination. A case where there are a plurality ofpaths to the transmission destination will now be described withreference to FIGS. 7 and 8. FIG. 7 illustrates the constitution of anadhoc network 2 of this modified example. FIG. 8 illustrates the dataconstitution of the routing table of this modified example andillustrates the content of the routing table of the cellular phone “A”shown in FIG. 7. The path management section 13 of this modified examplecreates or updates the routing table as follows on the basis of thetopology computed by the topology information management section 12.First, the path management section 13 derives the path to thetransmission destinations on the basis of the topology. Thereafter, thepath management section 13 selects, as optimum paths to the transmissiondestination, a plurality of paths within a predetermined specifiednumber in order starting with the path with the smallest number of linksto the transmission destination among the derived paths. The pathmanagement section 13 creates or updates the routing table on the basisof the respective selected paths. Here, the content of the routing tableshown in FIG. 8 will be described. For example, it is shown that, whenthe transmission-destination cellular phone is “F”, three paths whichare a path in which a link between “A” and “C” is the Next hop, a pathin which a link between “A” and “B” is the Next hop, and a path in whicha link between “A” and “D” is the Next hop are derived as optimum pathsfrom cellular phone “A” to cellular phone “F”. In this case, the QoSinformation collection section 14 of this modified example collects QoSinformation on the three paths. Further, the judgment section 15 of themodified example judges whether the respective QoS information collectedby the QoS information collection section 14 satisfies a predeterminedquality standard. As a result, even when communication is performed byusing a plurality of paths, only the QoS information on the pathsrequired for communication can be collected.

In addition, the QoS information collection section 14 of the aboveembodiment collects QoS information on all the links on the path derivedby the path management section 13 but is not limited to such QoSinformation. For example, only the QoS information on a portion of thelinks on the path derived by the path management section 13 may becollected. More specifically, for example, the collected QoS informationis stored in memory and the QoS information may be collected only forthe links for which QoS information has not been stored in memory. As aresult, the terminal resource and wireless resource consumption amountsand the load on the network can be reduced.

Furthermore, the judgment section 15 of the embodiment above sends apath request instruction requesting that another path be derived to thepath management section 13 upon judging that the QoS information doesnot satisfy a predetermined quality standard but is not limited to suchan action. For example, when it is judged that the QoS information doesnot satisfy the predetermined quality standard, the judgment section 15may reduce the level of the quality standard and, once again, judgewhether the QoS information satisfies the predetermined qualitystandard.

The disclosure of Japanese Patent Application No. 2005-255329 filed Sep.2, 2005 including specification, drawings and claims is incorporatedherein by reference in its entirety.

1. A wireless communication terminal, comprising: other terminalexistence confirmation means for confirming existence of anotherwireless communication terminal that allows mutual direct wirelesscommunication with the wireless communication terminal itself; topologyinformation management means for managing information relating to theother wireless communication terminal confirmed by the other terminalexistence confirmation means and information on topology of the networkthat is received from the other wireless communication terminal; pathderivation means for deriving the optimum path to a transmissiondestination on the basis of the topology information managed by thetopology information management means; and QoS information collectionmeans for collecting QoS information for at least a portion of the pathwhen a collect request instruction requesting that QoS information onthe path derived by the path derivation means be collected.
 2. Thewireless communication terminal according to claim 1, wherein the QoSinformation collection means collects the QoS information bytransmitting a packet in which at least a QoS item constituting acollection target is stored on the path derived by the path derivationmeans and by receiving, from the path, a packet in which at least QoSinformation corresponding with the QoS item is stored.
 3. The wirelesscommunication terminal according to claim 1, further comprising pathadoption means for adopting the path corresponding with the QoSinformation when the QoS information collected by the QoS informationcollection means satisfies a predetermined quality standard.
 4. Thewireless communication terminal according to claim 1, wherein the QoSinformation collection means collects the respective QoS information onthe plurality of paths when the plurality of paths are derived by thepath derivation means.
 5. A QoS information collection method,comprising: an other terminal existence confirmation step in which awireless communication terminal confirms existence of another wirelesscommunication terminal that allows mutual direct wireless communicationwith the wireless communication terminal itself; a topology informationmanagement step in which the wireless communication terminal managesinformation relating to the other wireless communication terminalconfirmed by the other terminal existence confirmation step andinformation on topology of the network that is received from the otherwireless communication terminal; a path derivation step in which thewireless communication terminal derives the optimum path to atransmission destination on the basis of the topology informationmanaged by the topology information management step; and a QoSinformation collection step in which the wireless communication terminalcollects QoS information for at least a portion of the path when acollect request instruction requesting that QoS information on the pathderived by the path derivation means be collected.